Velocity fluid vacuum seal, method, and apparatus



Aug. 10 1926. 1,595,485

0. MINTON VELOCITY FLUID VACUUM SEAL, METHOD AND APPARATUS OriginalFiled 1920 2 Sheets-Sheet 1 VTORNEY Aug. 10 1926. v 1,595,485

0. MINTON VELOCITY FLUID VACUUM SEAL, METHOD AND APPARATUS Ori inal ile1920 2 Sheets-Shet 2 INVENTOR 1 am am Ad N Patented Aug. 10, 1926.

UNITED STATES OGDEN MINTON, OF GREENWICH, CONNECTICUT.

VELOCITY FLUID VACUUM SEAL, METHOD AND APPARATUS.

Original application filed November 30. 1920, Serial No. 427,436.Divided and this application filed February 4, 1922, Serial No. 534,173.Renewed February 17, 1926.

This application is a division of my copending application Ser. No.427,436 filed- November 30, 1920, Case L.

My invention relates to the method of treating; materials in a vacuum,and more particularly to the method of protecting, the opening oropenings into the vacuum chamber, through which opening or openings thematerial to be treated is introduced and withdrawn from the chamber.

My invention rel-ates more particularly to a vacuum seal maintained bythe application of velocity head, i. e. the difference in pressurebetween the atmosphere and vacuum being balanced by the velocity head ofthe scaling medium. Through this seal the material to be treated in thevacuum chamber is passed in any suitable manner.

My invention turther relates more particularly to the method ofdryingsheet material, as a continuous web of paper either coming fromthe wet end of -a paper machine, or from a sizing vat, or from acoloring apparatus, coating machine or printing machine or directly froma roll of wet paper.

My invention further relates to a vacuum apparatus including a vacuumchamber having: passages extending from the said vacuum chamber and opento the atmosphere. These passages are protected by velocity fluid sealswhich prevent the admission of air into said vacuum chamber as the material to be treated is introduced and withdrawn through said seals.

My present invention further relates to employing a condensable fluid invelocity seals, such as for example steam.

My invention further relates to cmploying passages having restrictedareas merging); into prom'e'gsively larger areas between the atmosphereand the interior of the vacuum chamber, forming in etlect Venturinozzles, through which the fluid of the velocity fluid seals flows.

My invention further relates to collecting the steam and using it in thedrying drums or cylinders, or using it to heat the building, or I maycondense it, or otherwise dispose of it. I

My invention further relates,to certain steps, and combinations ofsteps, also to cer tain elements and combinations of elements. wherebythe method or processes herein dcsoribed may be carried out, as Well asto certain details of construction, all of which will be more fullyhereinafter described in the specification and pointed out in theclaims.

I have shown in the drawings, different forms of apparatus which may beused to carry out my improved method, but it is to be distinctlyunderstood that my invention is not to be confined to the particularform of apparatus, shown by way of illus tration.

In the accompanying drawings the same reference numerals refer tosimilar parts in the several figures.

Fig. 1 is a diagrammatic view of the simplest form of my invention;

Fig. 2 is a diagrammatic View, similar to Fig. 1, showing the web ofpaper or similar sheet material passing over drying drums or cylindersmounted in the vaccuum cham ber;

Fig. 3 is a steam radiator in which the steam from the velocity sealsmay be used to heat the building;

Fig.- 4 is a diagrammatic view of metric condenser.

The vacuum chamber A has a maintained therein in any suit-able byconnecting the pipe 1 with any suitable exhausting apparatus This vacuumchamber has two passages 22, 2 open to the atmosphere. Through thesepassages the material to be treated in the vacuum chamber A isintroduced and withdrawn. Of course it the passages were left unguardedthe vacuum in the vacuum chamber A would be broken.

My invention broadly consists in guarding the passages to the atmosphereby velocity fluid vacuum seals, the velocity of the fluid beingsutiiciently high to prevent any air working past the velocity seal intothe vacuum chamber.

In my invention suitable material may be introduced into and withdrawnfrom the vacuum chamber A through my velocity fluid seals 3, 3. It maybe treated in any suitable manner within the vacuum chamber. It may befed through the vacuum chamber continuously or not. I have shown by wayof example the material in the form of a continuous web which passescontinuously through the vacuum chamber A and the velocity fluid vacuumseals 3, 3. This a baro- YtlClllllll Web may be dried in the vacuumchamber. or coated, impregnated or treated in any other suitable manner,and may be fed into and out of the vacuum chamber in either direction asindicated by the arrows in Fig. 1.

These passages 2, 2 have restricted ar as 4, 4. Connected with theserestricted areas are nozzles 5, 5. The area of the passages 2, 2increases at 6, 6 adjacent the restricted areas 4, 4.

Steam which has no aflinity for or deleterious effect upon the web, orother material treated, is forced into the chambers 7, 7 through thepipe 50 and through the nozzles 5, 5 at sufficient velocity to preventair passing through the restricted area 4 and getting into the vacuumchamber A. The velocity required will depend on the vacuum maintained inthe vacuum chamber. Preferably I employ as near a perfect vacuum as Ican maintain, usually about 28 inches of mercury.

The steam passes through the nozzles 5 with comparatively high velocity.As the fluid reaches the portion 6 of comparatively large area itsvelocity is reduced. The passage 2 with its restricted area l. nozzles 5and portions of greater area (i is in effect a Venturi type nozzle. Thepassage 2 is of course wide enough to permit the free passage of thewidest web or other material to be passed into and out of the vacuumchamber.

The steam is collected in the chambers 8. 8 and is led off by the pipes9. 9 either to the steam drying drums or cylinders 10-, 11. 12, 13 and14, or it may be used to heat the radiators 15 to heat the building. orit may be connected to a vacuum pipe or condenser 16.

My invention is particularly adapted to be used in connection withdrying sheet material in the form of paper. though it is to bedistinctly understood that it is equally applicable to and covers dryingsheet material in the form of textile fabrics. as for example, dryingsuch fabrics after they have been washed or bleached or dyed. orotherwise treated by a liquid of some description.

The wet web of paper 17 coming directly from the wet end of a papermachine, or from a coloring apparatus. coating machine. printingmachine. or directly from a roll of wet paper is fed to the vacuumchamber A through the velocity fluid seal 3 at the left of Fig. 1, thenheated and dried in the vacuum chamber A and then out through the secondvelocity fluid seal 3 at the right of Fig. 1.

When a wet web of paper 17 coming from any source, such as that abovedescribed, is to be dried. I preferably pass it through the velocityseal at the left of Fig. 2 and into the vacuum chamber A. The web 17then passes in contact with the heated drying drums or cylinders 10, 11,12, 13 and 14; where it is completely dried, and then out through thevelocity seal at the exit end of the vacuum chamber A.

In this form of my invention the material to be dried is completelyprotected by the upper guard belt or felt 20, and the lower guard beltor felt 21 as it passes into and out of the vacuum chamber A. The lowerguard felt or belt 21, in its passage through the vacuum chamber,cooperates with the drying drums or cylinders 10. 12 and 14 and incontact with the guide rollers 22. 23. 24. 29. 25. 26, 27. 28 and thenceout through the velocity seal at the exit end of the vacuum chamber. andaround the guide rollers 30, 31. 32 and 33 where it again meets theupper felt or belt 20, and thence again through the vacuum chamber A. 7

The upper felt or belt 20, with the lower belt 21 protects the web ofmaterial 17 as it passes through the entrance velocity seal andcooperates with the drying drums or cylinders 10. l1. l3 and 1 1. On theperiphery of the drying drum or cylinder 11 it again meets the lowerfelt or belt 21, so that the web 17. when cooperating with this thyingdrum or cylinder 14, is again protected by both the upper and lowerguard felts or oelts 20 and 21 which continue to protect it until theweb of dry paper r other material. passes through the exit velocityseal, hat on the right of Fig. 2.

The upper belt or felt 20, after passing around the drying drum orcylinder 11 cooperates with the guide rollers 35, 36, 37 and 38. Afterthis upper belt or felt 20 passes through the exit velocity seal itcooperates with the guide rollers 39. 40, 41. 4-2, 43 and +4. where itagain meets the web 17 and the lower belt or felt 21.

My method possesses many advantages not present in processes heretoforeused for many years in the drying of paper.

The evaporation process, which is characteristic of the so-called loftdrying of paper, has many fully recognized disadvantages, and yet it isused today and has been in 18C for many years. In this method the wetpaper is taken from the paper machine, cut into sheets. hung on poles,carried to the drying room where it is subjected to hot air at about 130F. for about 48 hours. and when dry. each sheet is separatelycalendered. Although possessing the advantage of drying at acomparatively low temperature. whereby the moisture is slowlyevaporated. loft drying is obviously very inelli- :rent and costly.because it requires many Separate manipulations, is extremely s ow. usesextensive floor space and wastes heat.

The process which is employed in the ordinary paper machine in commonuse, is likewise subiect to many disadvantages. In such machine, the wetpaper as it comes proximately 5.3 pounds gauge pressure, at "which thesteam has a temperature of 228 F., giving a difference of temperature(928- 219") of only 16 F. lVith this slight difference of temperaturethe transfer of heat is extremely slow, and hence it is necessary toemploy many drying cylinders, in board machines often one hundred, andin news print machines, forty or more.

Also due to convection and conduction losses, as well as those incidentto leaks in the piping system and other inefficiencies, the heatactually required for atmospheric drying of a. ton of wet paper, is verymuch in excess of the theoretical requirement. The thermal efficiency ofatmospheric drying by steam heated cylinders is therefore very low.Furthermore, the steam produced from boiling the water out of the paper.is driven off into the operating room, and although fans and exhaustersare employed. at large expense for power and maintenance, the roomatmosphere is so constantly saturated with moisture as to rust andultimately destroy all iron and steel materials, and produces anexceedingly disagreeable and unhealthy atmosphere in which to work. Itis well known that the minimum temperature 212, the atmospheric boilingpoint of water, is positively in iu rious to, and results in oxidizing,the fibres of the paper, the strength of which is vastly improved whenthe paper is dried at lower temperatures. as in loft drying. This atmospheric drying process requires large ini tial cost for cylinders.felts, and other necessary equipn'icnt, and extensive floor space. andresults in the consumption of large amounts of power, and great cost foroperation. maintenance and repairs.

In my improved vacuum drying method 1 contemplatemaintaining within thechamber a va uum of about 22%" of mercury. in which 1 water boils at 100F.. and supplying the drying cylinders with steam at 5.3 pounds gaugepressure, producing a temperature of 228 F. The temperature differencebetween the temperature of the steam in the cylinders and that of thepaper. is therefore, 128 F. in my vacuum method. or 8 times greater (16F. 8:.1.28' F.) than the temperature difference in atmospheric drying.In my improved method the paper dries approximately 8 times faster thanin atmospheric drying. and I require only about oneeighth the number ofdrying cylinders to dry paper at the same rate of speed. I am able todry paper with 5 cylinders in the same time required of 40 cylindersdrying at atmospheric pressure, resulting in great economics in cost ofthe machine, floor space and of necessary piping, felts, auxiliaryequipment, and particularly in power and maintenance charges.

The thermal efliciency of my vacuum method is very much greater thanthat of the atmos 'iheric cylinder drying heretofore in universal usefor drying paper. Theoretical- 1v. it requires about 5287 pounds ofsteam to dry one ton of paper at atmospheric pressure. but to compensatefor convection and conduction losses, and those due to leaks in thepiping system. and other inefficiencies, it K has been shown in practicethat about 10.600 pounds are required.

In my method, using a vacuum of about 28", the convection, conductionand piping losses are exceedingly small and the total stream required todry a ton of paper by my method is approximately 5200 pounds.

It is an ef-ttablished fact that paper dried at low temperatures is muchstronger than when it is dried at the high temperatures used in papermachine atmospheric drying. Paper dried in a vacuum of 28", or at atemperature of about 100 F. as in my method, is very much stronger thanpaper dried at atmospheric pressure, when the steam in the driers is at228 F. \Vhen paper is dried by my method, therefore, a cheaper finish orstock can be used and still produce a paper equal in strength toatmospheric dried paper, in which a higher grade finish or stock isused. In making newsprint paper, I am able to dispense with aconsiderable portion of the more expensive sulphite pulp, as this can bereplaced with the cheaper ground wood pulp. By my method I also reducethe number of breaks in the web as it passes over the cylinder.

l urthcrmore. in my method there is a great saving of heat (or steam)because the process is carried on in a vacuum chamber which acts on theprinciple of a thermos bottle, and the steam and vapors driven out ofthe wet paper are caught in the closed vacuum chamber, and conductedaway to the condenser. The operating room is free from steam, humidityand heat, and fans. and exhaustcrs are dispensed with. In the use of mymethod the apparatus is at all times operating under definite humidity,the control of the drying can be closely standardized. and the moisturecontent in the paper carefully regulated.

Some of the modern open air dryers are equipped with a blower system bywhich air, either heated or not, is blown through the dryer section,which will lower the tempera ture at which the water is evaporated fromthe paper much below 212 F. and may, in some cases. reduce thetemperature of evaporation as low as 180 F. or lower.

&

Having pointed out the many advantages of my method and apparatus overthose heretofore used. it will be apparent that the use of my inventionresults in great economy in the initial cost of apparatus and in largesavings in cost of operation. maintenance and repairs.

Having thus described this invention in connection with difi'erentillustrative embodiments thereof. to the details of which I do notdesire to be limited. what is claimed as new and what is desired tosecure by Letters Patent is set forth in the appended claims.

What I claim is:-

1. The method of sealing against the admission of air into a vacuumchamber having openings for the passage of material to be treated insaid chamber. consistingv in preventing the admission of air throughsaid openings by causing a condensable medium to flow through saidopenings against. the pressure of the atmosphere.

2. The method of sealing against the admission of air into a vacuumchamber having openings for the passage of material to be treated insaid chamber. consisting in preventing the admission of air through saidopenings by causing steam to flow through said openings against thepressure of the atmosphere.

3. The method of sealing against the admission of air into a vacuumchamber having openings for the passage of material to be treated insaid chamber consisting in preventing the admission of air through saidopenings by causing steam to flow through said openings against thepressure of the an mosphere and then condensing the steam.

4. The method of sealing against the admission of air into a vacuumchamber having openings for the passage of material to be treated insaid chamber. consisting in preventing the admission of air through saidopenings by causing steam to flow through said openings against thepressure of the atmosphere and then utilizing the steam to heat thevacuum chamber.

5. The method of continuously drying sheet material consisting infeeding it into and out of a vacuum chamber through a condensablemedium. and causing said condensable medium to flow against the pressureof the atmosphere and prevent air working into the vacuum chamber, anddrying the sheet material in the vacuum chamber.

6. The method of continuously drying sheet material consisting incontinuously feeding the sheet material into and out of openings in thevacuum chamber. drying the sheet material in the vacuum chamber, andpreventing the admission of air through said openings by causing steamto flow through said openings against the pressure of the atmosphere.

i. The method of sealing against the ad-, mission of air into a vacuumchamber having openings for the passage of material to be treated insaid chamber. consisting in preventing the admission of air through saidopenings by causing a heated condensable medium to flow through saidopenings against the pressure of the atmosphere.

8. The method of continuously drying a web of wet paper consisting incontinuously feeding the web of wet paper into and out of openings inthe vacuum chamber, drying the web in the vacuum chamber, and preentingthe admission of air through said ioenings by causing steam to flowthrough said openings against the pressure of the atmosphere.

9. In a vacuum apparatus the combination of a vacuum chamber having oneor more openings for the admission and with rirawal of material into andfrom said vacuum chamber to be treated. and one or nore velocity fluidseals protecting said opening or openings and preventing the admissionof air into said vacuum chamber.

10. In a vacuum apparatus the combination of a vacuum chamber having oneor more openings for the admission and withdrawal of material into andfrom said vacuum chamber to be treated, and one or more velocity tluidseals protecting said opening or openings and preventing the admissionof air into said vacuum chamber and means to insure that said velocityfluid seals produce an aspirating effect on any air that might becontained in the vacuum chamber.

.1. In a vacuum apparatus the combinaiion of a vacuum chamber having oneor more openings for the admission and withirawal of material into andfrom said vacuum chamber to be treated, and one or more velocity tluidseals protecting said open ng or openings and preventing the admissionof air into said vacuum chamber and means to collect and condense thefluid of the seal.

12. In a vacuum apparatus the combination of a vacuum chamber having oneor more restricted passages similar to a Venturi nozzle connected withthe vacuum chamber and through said restricted passage or passages thematerial to be treated in the acuum chamber is adapted to pass. andmeans to supply steam through said reitricted passage or passages atsufiicient velocity to prevent the admission of air into the vacuumchamber.

13. In a vacuum apparatus the combination of a vacuum chamber having oneor more openings for the admission and withdrawal of material into andfrom said vacuum chamber to be treated. and one or more heated velocityfluid seals protecting and opening or openings and preventing the ionadmission of air into said vacuum chamber. 14. In a vacuum apparatus thecombina tion of a vacuum chamber having one or more openings for theadmission and with- 5 drawal of material into and from said vacuumchamber to be treated, and one or more heated velocity fluid sealsprotecting said opening or openings and preventing the admission of airinto said vacuum chamber and means to heat the vacuum chamber by theexhausted heated fluid of the velocity fluid seals.

OGDEN MINTON.

